Cosmetic fixups for WAL usage work.

Reported-by: Justin Pryzby and Euler Taveira
Author: Justin Pryzby and Julien Rouhaud
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/CAB-hujrP8ZfUkvL5OYETipQwA=e3n7oqHFU=4ZLxWS_Cza3kQQ@mail.gmail.com

contrib/pg_stat_statements/pg_stat_statements--1.7--1.8.sql

@@ -43,7 +43,7 @@ CREATE FUNCTION pg_stat_statements(IN showtext boolean,
     OUT blk_read_time float8,
     OUT blk_write_time float8,
     OUT wal_records int8,
-    OUT wal_num_fpw int8,
+    OUT wal_fpw int8,
     OUT wal_bytes numeric
 )
 RETURNS SETOF record

contrib/pg_stat_statements/pg_stat_statements.c

@@ -189,7 +189,7 @@ typedef struct Counters
 	double		blk_write_time; /* time spent writing, in msec */
 	double		usage;			/* usage factor */
 	int64		wal_records;	/* # of WAL records generated */
-	int64		wal_num_fpw;	/* # of WAL full page image records generated */
+	int64		wal_fpw;	/* # of WAL full page writes generated */
 	uint64		wal_bytes;		/* total amount of WAL bytes generated */
 } Counters;
 
@@ -1432,7 +1432,7 @@ pgss_store(const char *query, uint64 queryId,
 		e->counters.blk_write_time += INSTR_TIME_GET_MILLISEC(bufusage->blk_write_time);
 		e->counters.usage += USAGE_EXEC(total_time);
 		e->counters.wal_records += walusage->wal_records;
-		e->counters.wal_num_fpw += walusage->wal_num_fpw;
+		e->counters.wal_fpw += walusage->wal_fpw;
 		e->counters.wal_bytes += walusage->wal_bytes;
 
 		SpinLockRelease(&e->mutex);
@@ -1824,7 +1824,7 @@ pg_stat_statements_internal(FunctionCallInfo fcinfo,
 			Datum		wal_bytes;
 
 			values[i++] = Int64GetDatumFast(tmp.wal_records);
-			values[i++] = Int64GetDatumFast(tmp.wal_num_fpw);
+			values[i++] = Int64GetDatumFast(tmp.wal_fpw);
 
 			snprintf(buf, sizeof buf, UINT64_FORMAT, tmp.wal_bytes);
 

doc/src/sgml/pgstatstatements.sgml

@@ -278,16 +278,16 @@
       <entry><type>bigint</type></entry>
       <entry></entry>
       <entry>
-        Total count of WAL records generated by the statement
+        Total number of WAL records generated by the statement
       </entry>
      </row>
 
      <row>
-      <entry><structfield>wal_num_fpw</structfield></entry>
+      <entry><structfield>wal_fpw</structfield></entry>
       <entry><type>bigint</type></entry>
       <entry></entry>
       <entry>
-        Total count of WAL full page writes generated by the statement
+        Total number of WAL full page writes generated by the statement
       </entry>
      </row>
 

doc/src/sgml/ref/explain.sgml

@@ -198,8 +198,8 @@ ROLLBACK;
     <listitem>
      <para>
       Include information on WAL record generation. Specifically, include the
-      number of records, number of full page image records and amount of WAL
+      number of records, number of full page writes and amount of WAL bytes
-      bytes generated.  In text format, only non-zero values are printed.  This
+      generated.  In text format, only non-zero values are printed.  This
       parameter may only be used when <literal>ANALYZE</literal> is also
       enabled.  It defaults to <literal>FALSE</literal>.
      </para>

src/backend/access/heap/vacuumlazy.c

@@ -676,7 +676,7 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 							 _("WAL usage: %ld records, %ld full page writes, "
 							   UINT64_FORMAT " bytes"),
 							 walusage.wal_records,
-							 walusage.wal_num_fpw,
+							 walusage.wal_fpw,
 							 walusage.wal_bytes);
 
 			ereport(LOG,

src/backend/access/transam/xlog.c

@@ -1258,7 +1258,7 @@ XLogInsertRecord(XLogRecData *rdata,
 	{
 		pgWalUsage.wal_bytes += rechdr->xl_tot_len;
 		pgWalUsage.wal_records++;
-		pgWalUsage.wal_num_fpw += num_fpw;
+		pgWalUsage.wal_fpw += num_fpw;
 	}
 
 	return EndPos;

src/backend/commands/explain.c

@@ -3343,7 +3343,7 @@ show_wal_usage(ExplainState *es, const WalUsage *usage)
 	if (es->format == EXPLAIN_FORMAT_TEXT)
 	{
 		/* Show only positive counter values. */
-		if ((usage->wal_records > 0) || (usage->wal_num_fpw > 0) ||
+		if ((usage->wal_records > 0) || (usage->wal_fpw > 0) ||
 			(usage->wal_bytes > 0))
 		{
 			ExplainIndentText(es);
@@ -3352,9 +3352,9 @@ show_wal_usage(ExplainState *es, const WalUsage *usage)
 			if (usage->wal_records > 0)
 				appendStringInfo(es->str, "  records=%ld",
 								 usage->wal_records);
-			if (usage->wal_num_fpw > 0)
+			if (usage->wal_fpw > 0)
 				appendStringInfo(es->str, "  full page writes=%ld",
-								 usage->wal_num_fpw);
+								 usage->wal_fpw);
 			if (usage->wal_bytes > 0)
 				appendStringInfo(es->str, "  bytes=" UINT64_FORMAT,
 								 usage->wal_bytes);
@@ -3366,7 +3366,7 @@ show_wal_usage(ExplainState *es, const WalUsage *usage)
 		ExplainPropertyInteger("WAL records", NULL,
 							   usage->wal_records, es);
 		ExplainPropertyInteger("WAL full page writes", NULL,
-							   usage->wal_num_fpw, es);
+							   usage->wal_fpw, es);
 		ExplainPropertyUInteger("WAL bytes", NULL,
 								usage->wal_bytes, es);
 	}

src/backend/executor/instrument.c

@@ -248,7 +248,7 @@ WalUsageAdd(WalUsage *dst, WalUsage *add)
 {
 	dst->wal_bytes += add->wal_bytes;
 	dst->wal_records += add->wal_records;
-	dst->wal_num_fpw += add->wal_num_fpw;
+	dst->wal_fpw += add->wal_fpw;
 }
 
 void
@@ -256,5 +256,5 @@ WalUsageAccumDiff(WalUsage *dst, const WalUsage *add, const WalUsage *sub)
 {
 	dst->wal_bytes += add->wal_bytes - sub->wal_bytes;
 	dst->wal_records += add->wal_records - sub->wal_records;
-	dst->wal_num_fpw += add->wal_num_fpw - sub->wal_num_fpw;
+	dst->wal_fpw += add->wal_fpw - sub->wal_fpw;
 }

src/include/executor/instrument.h

@@ -35,7 +35,7 @@ typedef struct BufferUsage
 typedef struct WalUsage
 {
 	long		wal_records;	/* # of WAL records produced */
-	long		wal_num_fpw;	/* # of WAL full page image writes produced */
+	long		wal_fpw;	/* # of WAL full page writes produced */
 	uint64		wal_bytes;		/* size of WAL records produced */
 } WalUsage;